Posted
by
Soulskill
on Friday November 04, 2011 @03:56PM
from the pretty-pictures dept.

An anonymous reader sends this excerpt from the HST site:
"A team of scientists has used the NASA/ESA Hubble Space Telescope to observe a quasar accretion disc — a brightly glowing disc of matter that is slowly being sucked into its galaxy's central black hole. Their study makes use of a novel technique that uses gravitational lensing to give an immense boost to the power of the telescope. The incredible precision of the method has allowed astronomers to directly measure the disc's size and plot the temperature across different parts of the disc."

Good memory there, I first heard this drivel about HST twenty years ago, when it was launched with the original warped mirror and before the "contact lens" was installed. Yeah, some pundit on the teevee made the predictably pedantic comment, and the very next day my college roommate spit out the "ditto", as a "very earnest and personal opinion", LOL.

I would say the mars rovers were a better bang for the buck, but hubble is a close second even with all the retrofits.

I still find it a shame that the last shuttle mission wasn't a trip to the hubble to bring it home. just like the shuttle were designed to do.

Other than for it to go into a museum, what would be the benefit of spending millions of dollars bringing 20-year-old technology back to earth (rather than letting it spend another 10 years in space)? Sure you can say stuff like "to see what the effects of 20 years in 0-gravity were" but we have other examples.

I would say put it in a museum to inspire kids to study STEM. Then again, perhaps someone should make a roving Hubble exhibit. Make a life size, non-working replica of the Hubble telescope, select a couple dozen of the most spectacular photos and print them poster-sized. Then go from town to town showing off what Hubble did and promoting exploring space. I'm not sure how much it'd cost to create a look-alike of the exterior of the Hubble, but I'm guessing it would cost much less than the amount it'd cos

The hubble is probably a lot heavier than a typical satellite, and I suspect you'd have to prep it so that it doesn't fall apart when subjected to stress, or damage the shuttle in the process.

Landing weight for any glider is obviously an issue (especially one already covered in ceramic tiles and carrying a pile of lifeless engines). Re-entry weight is another big issue, as well as center-of-gravity/etc. Every pound of mass on the shuttle is just that much more kinetic energy being converted to heat blasti

The scientific input of the rovers were close to zero. Yet during the same time a German team made a cartography of Mars underground resources, including large quantities of frozen water, yet no one talked about.

Not every satellite orbiting this or other planets was made by the US. Of course, lacking the original sources squabbling about what they might or might not have used is pretty much the definition of pointless.

And by the way, why would working together with NASA be any problem for determining who did what science? Last I heard, most European, Russian, Japanese and American

Not everyone is a nationalistic fanboy you know. French here but this is less important in my opinion than me being a techy and a science fan. I feel closer to Americans or Chineses who share my interests than to my xenophobic neighbour.

Actually, I am not complaining about how good NASA's PR department is, I am more complaining about how real technological and scientific innovation are not what interest the public nowadays.

The German experiment I am talking about was a device in the ESA mission to Ma

I would say the amount and variety of information we've obtained from Hubble absolutely dwarfs the limited exploration of the Mars rovers. The Deep Field [wikipedia.org] picture alone is more interesting than anything the rovers did.

Well, the effect has been known since 1979. It's just that everything lines up very rarely, it's amazingly effective when it works but you can't exactly move the lens so you only get to focus on what's exactly behind it. We are going to need bigger and better telescopes to solve the general case.

About 8 years ago I was using the Deep Field View [hubblesite.org] for my desktop wallpaper - there's a lot of gravitational lensing going on in there, if you look carefully. Ol' Albert was a pretty sharp one, a little sad he didn't live to see these sorts of images - I'm certain he'd be so stoked that he'd pump his fist and shout, "Yesssss!"

In the spirit of science I'll toast to his memory with a pint when I gets home tonight.

I'm all for Hubble and am very happy they did the "risky" last servicing mission but I was just wondering, could this be done from the ground?

With ground based scopes around 10m in diameter the light capacity (except on a cloudy day!) would far surpass the Hubble. Do the "artificial" star techniques not work well enough!? Or maybe the dwell time is too long? Or maybe these images are in a part of the spectrum that doesn't go through the atmosphere?

You're right in all of your suppositions. (Except for cloudy day--It's the cloudy nights you have to watch out for:)

Today's 10m class and tomorrow's 30m class telescopes can do a lot of what Hubble has done, especially when you factor in advanced AO systems like the one that was recently installed on Gemini South (one 50W laser split into 5 beams for correction over a large field). Anything on the ground is cheaper than in space.

Hubble, JWST, Chandra, and the others can see wavelengths that are absorbed by the atmosphere, no matter how high you are.

And integration time is a huge factor. The Ultra Deep Field image was over 1.1 million seconds of exposure. It's just not practical to do exposures like that from the ground.

The Ultra Deep Field image was over 1.1 million seconds of exposure. It's just not practical to do exposures like that from the ground.

The 1.1 million seconds is interesting. As soon as I saw the number I wanted to figure out how many days that was. Turns out it is ~12.73 days. That time frame really made me think that whomever was controlling the scheduling kicked off this long picture very early Monday morning, at the start of their work week, and then waited till the following Friday, before heading home for the start of the weekend, to end the exposure.

I've been working business hours for just long enough this seemed like it must be

I process data from the Hubble and also from the ESO Southern Observatory. And that images (and hence data) from the Hubble are still very much clearer than what the ESO SO can take. Not having to look through an ocean of air makes a huge difference.

Since Hubble was launched, advances in adaptic optics have made it possible to capture images of similar quality from the ground. However, there is a trade-off. The nature of adaptive optics means that they are very good for imaging small regions of the sky. This is great if you want to examine a specific object with pinpoint accuracy. However, adaptive optics isn't good if you want to survey large areas of the sky - a space-based telescope such as Hubble is still the best choice for that kind of work. So i

Looking at that image, the two main features look like symmetric interference patterns, fairly simple ones. Why not do the Fourier (or other) analysis to recompose the original light signals?

You might be right, but I think it is possible those are jets being emitted from the black hole... they say they were able to measure the temp across parts of it, the hottest parts blasting out of it could be those bright points on the image. It would be quite interesting if that was ever confirmed.

The image in the article looks like one'd expect a disk to look like through a lens. That means that it is a raw image (or a reconstruction of what a raw image is like) from the study, not the resulting render of the disk.

Right, that's what I'm saying: a the light of a disc's image interfering with itself in a lens.

What I'm asking is why they don't recompose the image of the disc to show us? I'm not nearly as interested in the light after gravity has lensed it, even if that's the technique this project used to get the disc. The point of the effort is the image of the disc.

As the black hole feeds it churns all the matter around it causing it to radiate light. As it pulls stuff in not all of it goes into the event horizon, some just whips around and flys out and smashes into the other incoming matter. This is what makes it a quasar, it is the active galactic nucleus. If its not feeding like the black hole in our galaxy then it would indeed be black. There is some good vids of stars orbiting the invisible mass at the centre of our galaxy actually.
http://www.google.ie/url?sa=t [google.ie]

These observations show a level of precision equivalent to spotting individual grains of sand on the surface of the Moon.

Hubble probably wasn't designed for this sort of thing, but imagine a space telescope that's designed for observing objects inside our solar system. It'd be like putting the moon under a microscope, or exploring Mars and getting detailed survey results without the time and expense of sending a probe there. Is it possible? Is it being planned?

imagine a space telescope that's designed for observing objects inside our solar system. It'd be like putting the moon under a microscope, or exploring Mars and getting detailed survey results without the time and expense of sending a probe there. Is it possible?

Not by traditional means, at least. Essentially, the resolving power of any telescope is limited and the only way to increase it is to use larger lenses. Looks like some articles disagree on the exact size needed for certain features, but google f

These observations show a level of precision equivalent to spotting individual grains of sand on the surface of the Moon.

Hubble probably wasn't designed for this sort of thing, but imagine a space telescope that's designed for observing objects inside our solar system. It'd be like putting the moon under a microscope, or exploring Mars and getting detailed survey results without the time and expense of sending a probe there. Is it possible? Is it being planned?

We don't happen to have any of those between us and Mars, so it won't work. And, I'm just a little too foggy for the accuracy vs. precision discussion at the moment, but even if they managed to magnify these things so extraordinarily as to look at grains of sand on the moon, I doubt they really know if they're looking at coarse sand, fine sand, or small pebbles. After all, how

I appreciate the power of gravitational lensing, but to presume that you have anything resembling an accurate measurement when using it, unless they mean precisely, within an order of magnitude, or two.

According to Einstein's General Theory (I think), the mass of an object increases as it approaches the speed of light. The amount of this increase depends on the position of the observer.
My question is: At what point does the increasing mass begin to warp the space around it (relative to the observer)?
Thanks in advance for any input,
Roy